1. Field of the Invention
The present invention relates to photoreactive resin compositions which are used for forming conductive patterns, methods for making circuit substrates in which conductive films are formed using the photoreactive resin compositions, and methods for making ceramic multilayer substrates in which conductive films are formed using the photoreactive resin compositions.
2. Description of the Related Art
Recently, miniaturization and improved performance have been strongly required for high-frequency electronic components used for mobile communication apparatuses, satellite broadcast receivers, computers, etc. With respect to the wiring patterns of high-frequency electronic components, higher wiring density and higher signal transmission speed have been demanded. In order to achieve such higher wiring density and higher signal transmission speed, finer wiring patterns must be formed and the thickness of wiring patterns must be increased.
In order to form fine thick wiring patterns, photolithography using a photoreactive resin composition is effectively employed. In a photolithographic process, a photoreactive resin composition containing a powdered inorganic component (powdered conductive metal for forming wiring patterns or powdered glass for forming via-holes) and a photoreactive organic component including an alkali-soluble polymer, a monomer having an ethylenically unsaturated double bond, a photoreaction initiator, etc., is applied onto a substrate and is then dried. Subsequently, patterning is performed by exposure through a mask, followed by development with an alkaline developer, and then firing is performed to form a wiring pattern with a predetermined shape. An example of photolithographic processes is disclosed in Japanese Unexamined Patent Application Publication No. 5-67405.
However, when such a photoreactive resin composition is exposed and developed, extraneous matter remaining on the substrate, i.e., residue after development, gives rise to a problem. In particular, when a powdered base metal is incorporated in the photoreactive resin composition, it is not possible to prevent a residue after development due to aggregation of the powdered base metal.